Several compositions have been developed to produce an artificial fingernail which can be applied to a natural nail plate for the purpose of protecting, adorning; extending, and/or decorating the nail plate. In general, these compositions are formed-from a liquid binder comprising the following ingredients:                a) a monomeric acrylate of methacrylate ester such as methyl methacrylate, ethyl methacrylate, tetrahydrofufuryl methacrylate, methoxyethyl methacrylate, methoxyethoxyethyl methacrylate and similar others;        b) a di, tri or multifunctional acrylate or methacrylate ester such as ethylenegylcol dimethacrylate, diethyleneglycol dimethacrylate, 1,4-butanediol dimethacrylate, trimethylolpropane trimethacrylate, and similar others; and        c) a tertiary amine accelerator such as N,N-dimethyl-para toluidine.        
The liquid binder is combined with a polymeric filler generally comprising the following ingredients:                a) a finely divided polymeric methacrylate (e.g., poly (ethyl methacrylate)) or copolymeric methacrylate (e.g., a 70:30 molar ratio comprising poly(ethyl-co-methyl) methacrylate); and        b) an organic peroxide polymerization initiator such as benzoyl peroxide.        
The known compositions are used to form an artificial nail on a nail plate by dipping an application brush first in the liquid binder and then into the polymeric filler, so as to form a wetted mass on the brush. The wetted mass is then transferred to a prepared nail plate, where the wetted mass is manipulated to achieve the desired shape. Forms and molds may be positioned about the nail plate prior to application of the wetted mass to facilitate in extending the artificial nail beyond the nail plate.
The known compositions are based on the free-radical driven polymerization of acrylate monomers around acrylate polymers and/or copolymers. Accordingly, when the liquid binder is mixed with the solid polymer filler, the organic peroxide from the polymer filler interacts with the tertiary amine catalyst in the liquid binder to produce free radicals which catalyze the polymerization reaction. Polymerization speed may be regulated so as to yield acceptable times for working the wetted polymer filler into the desired shape by adjusting the concentrations of the initiator and accelerator present in the composition. Acceptable durations for total polymerization typically range from 3 to 5 minutes from the initiation of the reaction, a time short enough to decrease the likelihood of damage to the finished surface but long enough to allow the user sufficient time to shape the composition.
Optional components may be added to the general composition to impart specifically desired properties to the composition and/or the final product. For example, polymerization inhibitors (e.g., methyl ether of hydroquinone or butylated hydroxytoluene (BHT)), dyes, and ultraviolet light stabilizers are often added to the liquid binder. Likewise, pigments (e.g., titanium dioxide), secondary polymers (e.g., polyvinyl acetate), and flow property modifiers (e.g., fumed silica) are typically added to the polymeric filler.
Although the onset and speed of polymerization may be increased by increasing the levels of both the organic peroxide and the tertiary amine, an excess of these compounds may generate chromogenic substances during the polymerization reaction. Therefore the limiting consideration for improvement of the speed of polymerization is the concomitant discoloration which occurs when high levels of the organic peroxide and tertiary amine are used. To overcome the problem of discoloration, a non-yellowing composition for artificial nails has been described. The composition relies on the ability of free-hydroxyl moieties in the liquid binder to speed polymerization and initiation, thereby allowing lower concentrations of the organic peroxide and tertiary amine accelerator to be used. Hydroxyl groups are present in the formulation as saturated and/or unsaturated alcohols. A typical example of such a non-yellowing composition comprises a liquid binder and a polymer filler having the following compositions, in weight percent:
Liquid binder portion10–95%of a methacrylate monomer; 1–50%of a methacrylate polymer crosslinker (e.g., multi-functional); 1–50%of an alcohol (e.g., saturated or unsaturated methacrylatealcohols);0.1%–5%  of a tertiary amine polymerization catalyst (e.g.,Q.S.dimethyl-p-toluidine and dihydroxyethl-p-toluidine); andof a methyl-ethyl-hydroxyquinone (a polymerizationinhibitor used as a regulator for product stability toprevent polymerization of the liquid binder prior tointended use)Polymer filler portion95–99%of a finely divided polymer selected from the polyalkylmethacrylates and/or co-methacrylates;0.1–5.0%of an organic peroxide, such as benzoyl peroxide; andQ.S.of other ingredients such as whiteness enhancers (e.g.,titanium dioxide and other pigments), secondarypolymers (e.g., polyvinyl acetate) and flow modulators(e.g., fumed silica).
In addition, photopolymerizable compositions have been formulated. Those compositions contain an ultraviolet light-activated hardening accelerator to accelerate the polymerization reaction. Light-activated accelerators generally contain 40–90% of a monomer selected from the methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, furfuryl, tetrahydrofurfuryl, and glycidal esters of acrylic acids, and the alkyl substituted acrylic acids in which the alkyl chain length is 1–4 carbons; 3–40% of a monomer selected from the group consisting of the esters of polyhydric alcohols having from about two to about four hydroxyl groups, and preferably acrylic acid or an alkyl-substituted acrylic acid in which the alkyl group has from one to four carbon atoms; and from 0.1–30%, and preferably from 0.2–5% by weight, of a photopolymerization initiator, such as benzoin, benzoin methyl ether, or other benzoin derivative.
Further, compositions have been described which reduce harmful or offensive odors associated with traditional artificial nail formulations. This class of acrylic nail preparation relies on alkylmethacrylate monomers (AMES) in addition to hydroxyalkyl methacrylates (HAMES) to temper odor production, as well as precipitous polymerization.
Regardless of the composition used, a problem associated with the known artificial nail compositions arises because the acrylic nails limit oxygen diffusion into, and CO2 and water diffusion away from, the normally-permeable natural nail plate. In particular, a build up of water at the natural nail/artificial nail interface presents a warm, moist environment in which pathogens may thrive. Furthermore, organic solvents used in the artificial nail compositions can degrade the natural components of the nail which would normally prevent such infections. Therefore, moisture and biotic contaminants (e.g., bacteria, molds, spores, viruses and fungi) can become trapped on the nail plate, between the artificial nail and the nail plate, in the nail groove, and even in interstitial spaces between keratinocytes of the natural nail. The trapped contaminants can cause polymicrobial infections of the nail plate which result in discoloration and destabilization of the natural nail. Discoloration is of primary concern in the application of acrylic nails, whose thin polymer matrices are often translucent and reveal color defects of the natural nail. Destabilization of the natural nail plate increases the likelihood that mechanical sheer force on the attached artificial nail will cause painful tearing of the natural nail away from the living tissue of the nail bed. Onychomycosis is just one example of the myriad of microbial etiologies of nail disfigurement requiring expensive, prolonged medical therapy, which is not always innoucuous and can even be toxic. Moreover, such therapy often provides less than satisfactory cure rates and patient tolerance. Additionally, from a commercial standpoint, professional nail technicians and consumers of professional nail care products recognize that lifting and chipping of artificial nails is exacerbated by organic contaminants which grow at the interface of the natural nail and the artificial nail.
In light of the foregoing, it would be highly beneficial to provide a composition for forming an artificial fingernail, and methods for preparing and using the same, wherein the composition and methods provide for prophylaxis against microbial infections of the nail plate due to the entrapment of organic contaminants on or beneath the artificial nail. Further, the composition and methods should provide a continued prophylaxis against acquired organic contamination after the application of the artificial nail. The composition and methods should also provide for an antimicrobial agent that is incorporated into the artificial nail but which is not covalently bound to the artificial nail so that the antimicrobial agent is available for diffusion from the artificial nail. Preferably, the composition and methods should enable the artificial nail to be formed prior to application of the artificial nail. The present invention is directed to these, as well as other, important needs.